Final Report of the Sustainable Fisheries Goal Implementation Team Invasive Catfish Task Force. Winter 2014

Transcription

1 Final Report of the Sustainable Fisheries Goal Implementation Team Invasive Catfish Task Force Winter

2 Invasive Species Task Force Members Bruce Vogt, Chair, National Oceanic and Atmospheric Administration Chesapeake Bay Office (NCBO) Nancy Butowski, Maryland Department of Natural Resources (MD DNR) Ellen Cosby, Potomac River Fisheries Commission (PRFC) Mary Fabrizio, Virginia Institute of Marine Science (VIMS) Matt Fisher, Delaware Department of Natural Resources and Environmental Conservation (DNREC) Greg Garman, Virginia Commonwealth University (VCU) Bob Greenlee, Virginia Department of game and Inland Fisheries (VDGIF) Joe Grist, Virginia Marine Resources Commission (VMRC) Mary Groves, Maryland Department of Natural Resources (MD DNR) Robert Hale, Virginia Institute of Marine Science (VIMS) Mike Hutt, Virginia Marine Products Board Matt Ogburn, Smithsonian Environmental Research Center (SERC) Danny Ryan, District of Columbia Department of the Environment (DC DOE) Geoffrey Smith, Pennsylvania Fish and Boat Commission (PFBC) Howard Townsend, National Oceanic and Atmospheric Administration Chesapeake Bay Office (NCBO) Andrew Turner, National Oceanic and Atmospheric Administration Chesapeake Bay Office (NCBO) Steve Vilnit, Maryland Department of Natural Resources (MD DNR) Special thanks to Mary Fabrizio and Greg Garman who authored significant portions of the report documenting the history, biology and invasiveness of blue and flathead catfishes. 2

3 Table of Contents Executive Summary... 4 Introduction, Purpose, and Scope... 9 Invasive Catfish Task Force and Objectives Overview of Invasive Catfishes (Blue and Flathead Catfishes) in the Chesapeake Bay Introduction, Distribution, and Expansion Invasiveness and Ecological Impacts Current Management Efforts Regulations and Policies Commercial and Recreational Fisheries Research and Monitoring Communication and Outreach Recommendations Conclusion Appendix A: Summary of Current Research and Findings Appendix B: Logic Model Literature Cited

4 Executive Summary The Problem Federal Executive Order 13112, adopted in 1999, defined an invasive species as a non-native species whose introduction does or is likely to cause economic or environmental harm or harm to human health. There are several species in the Chesapeake Bay watershed that meet these criteria and pose a risk to the ecology and economy of the region; however, this report focuses on the blue catfish (Ictalurus furcatus) and flathead catfish (Pylodictis olivaris). Both catfish species are considered invasive to the Chesapeake Bay as they are not native to this region and have demonstrated negative impacts on native species and the ecology of the Bay. Flathead catfish were introduced into the James River in the late 1960s, whereas blue catfish were introduced into the James, Rappahannock, and York Rivers in Virginia during the 1970s and 1980s. The catfish were introduced to establish recreational fisheries in Virginia; however, these catfish quickly spread throughout the region into nearly every major tributary. Both blue and flathead catfishes are long lived and are predators that feed predominantly on native fishes and shellfish, which may have dire consequences for fishery industry as well as other ecological and economic interests in the Chesapeake Bay region. The expanding range and increasing population size of these catfish, particularly of blue catfish, have resource managers concerned that damage to Chesapeake Bay resources may be irreversible without management intervention. The Need Currently, a comprehensive management strategy for invasive catfishes is lacking. Further, there is a strong need for coordination across Chesapeake Bay management jurisdictions to work together and engage the public to effectively reduce the spread and minimize the ecological and economic harm from blue and flathead catfishes. Developing management strategies should incorporate current research studies and monitoring efforts to improve knowledge and evolve management approaches into the future. 4

5 The Invasive Catfish Task Force The Invasive Catfish Task Force (ICTF) was established in 2012 by the Sustainable Fisheries Goal Implementation Team (Fisheries GIT) of the Chesapeake Bay Program and tasked with developing and recommending management options that could be applied Bay-wide in response to the spread of invasive blue and flathead catfish populations in the Chesapeake Bay region. The ICTF is comprised of members from the state and local fishery management jurisdictions of Maryland, Virginia, Pennsylvania, Delaware, and the District of Columbia, representatives from the Potomac River Fisheries Commission and National Oceanic and Atmospheric Administration (NOAA), academic experts from the Virginia Institute of Marine Science (VIMS), Virginia Commonwealth University (VCU), Smithsonian Environmental Research Center (SERC), and seafood marketing specialists from Maryland Department of Natural Resources and the Virginia Marine Products Board. The ICTF met several times in-person and via teleconference to compile and evaluate existing information on blue and flathead catfishes and to discuss potential management options. The ICTF also briefed the Fisheries GIT and stakeholders on draft recommendations during the preparation of this report. The ICTF developed recommendations to address the following four objectives: 1. Slow and reduce the spread of invasive catfishes into currently uninvaded waters; 2. Minimize the ecological impacts of invasive catfishes on native species; 3. Promote a large-scale fishery to significantly reduce abundance of invasive catfishes and provide economic benefits to the region; and 4. Increase outreach and education and broadcast the message that blue and flathead catfishes are not native to the Chesapeake Bay and negatively impact native ecosystems. Outreach is also needed to emphasize that public assistance is needed to avoid additional unauthorized introductions within the Bay watershed. 5

6 Recommendations Recommendation 1: Removal from Priority Areas We recommend that jurisdictions (federal, state and local) work together to design and implement targeted fishery-independent (non-commercial market) removals of invasive catfish in areas of significant ecological value (i.e. spawning and nursery habitat areas for anadromous species). Well-planned, intensive, and repeated removals of invasive catfishes may have the potential to reduce populations and lessen their impacts on important native species. We further recommend these removals be conducted as pilot projects or studies to develop, test, quantify, and evaluate removal methods for invasive catfishes. As part of this effort, we recommend that jurisdictions identify areas of significant ecological and economic value for native fish and shellfish species and their habitats and consider preventative measures to reduce the risk of invasive catfish introductions and expansion in these areas. Recommendation 2: Develop Commercial Fisheries We recommended that efforts and incentives to develop a large-scale, commercial fishery be accelerated and coordinated across jurisdictions. Harvest incentives exploiting the growing populations of invasive catfishes have the potential to reduce populations while also providing economic benefits to the region. This will require more immediate and coordinated action across jurisdictions to identify markets, increase the value of the fishery, and remove factors (e.g. lack of processing facilities) that are currently limiting expansion of the existing smallscale fishery. A critical element of this recommendation is developing a fishery that is dedicated to reducing invasive catfish populations over the long term. We recommend a workshop be held with current and prospective fishers, fishery managers, and economists to identify the steps needed to expand the current fishery and make it economically feasible. We note that Washington, D.C. restaurants have been successful in promoting the blue and flathead catfish as local, fresh catfish on their menus and suggest implementing similar measures throughout the Bay watershed. 6

7 Recommendation 3: Evaluate Removal Methods We recommend jurisdictions consider options to incentivize increased harvest operations for invasive catfishes by small boat operations and electrofishing. These options could be further discussed as a part of the workshop suggested in Recommendation 2. We note that the Fishery Resource Grant Program of Virginia Sea Grant has funded studies exploring the feasibility of using electrofishing gear for harvest of blue catfish. Similar evaluations of gear efficiency could be promoted within additional organizations. Recommendation 4: Develop Monitoring and Response Plans We recommend jurisdictions establish monitoring programs dedicated to identifying and tracking invasive catfish distributions and population status. There are currently few dedicated monitoring and survey efforts for invasive catfishes; accordingly, we also recommend developing early detection and response programs for ecologically significant areas. In addition, invasive catfish research and management efforts in the Chesapeake Bay should be synthesized and used to improve effective implementation and refinement of the management options outlined in this report. Recommendation 5: Evaluate Habitat Connectivity We recommend an evaluation of the effectiveness of existing barriers to invasive catfish spread (i.e. dams) and suggest that the benefits of barrier removal be weighed against the risk of damage to areas of significant ecological value by invasive catfish range expansion. We suggest formal coordination between invasive catfish experts and the Fish Passage Workgroup of the Chesapeake Bay Program Habitat Goal Implementation Team to identify barriers and develop ecosystem-based recommendations that address the risk of additional invasions following dam or other barrier removal efforts. Recommendation 6: Review Fishing Policies and Regulations We recommend a cross-jurisdictional review of current fishing policies and regulations to identify and address current regulations that may facilitate the persistence and expansion of 7

8 invasive catfish populations. This review should also evaluate the efficacy of communications and enforcement of the current regulations regarding the illegal transport of live fish. Recommendation 7: Develop Communication Strategies We recommend jurisdictions make information on invasive catfishes more accessible, consistent, and clearer to anglers and the general public. Information on invasive catfishes is difficult to find and not well coordinated across jurisdictions. Particular attention should be paid to the correct identification of blue catfish (especially), distinguishing them from native species. We suggest an immediate effort be made to convene communication experts from the Chesapeake Bay region to identify inconsistencies in messaging and develop an aggressive communication campaign to increase public awareness. This campaign should be paired with the development of a web portal that provides the public, researchers, and resource managers access to current information on invasive catfishes. We believe that these recommendations, once implemented, will form the foundation to address the many challenges associated with the catfish invasion of the Chesapeake Bay. Furthermore, lessons learned during implementation will allow for adaptation and improvements. We suggest that the Fisheries GIT Executive Committee prioritize these recommendations and determine the most effective way for to implement the actions that result. 8

9 Introduction Invasive species are defined as non-native species that can cause harm to the environment, economy, or to human health according to federal Executive Order 13112, signed in There are several species in the Chesapeake Bay watershed that meet these criteria and pose a risk to the ecology and economy of the region; however, this report focuses on the blue catfish (Ictalurus furcatus) and flathead catfish (Pylodictis olivaris), both considered invasive to the Chesapeake Bay as they are not native to this region and have demonstrated negative impacts on native species and the ecology of the Bay. Flathead catfish were introduced into the James River in the late 1960s, whereas blue catfish were introduced into the James, Rappahannock, and York Rivers in Virginia during the 1970s and 1980s. Both species were introduced to establish recreational fisheries in Virginia; however, these catfish quickly spread throughout the region into most major tributaries. These invasive catfishes are long-lived predators that feed predominantly on native fishes and shellfish. The expanding range and increasing populations, particularly of blue catfish, have resource managers concerned that without management intervention, damage to Chesapeake Bay resources may be irreversible. Purpose The purpose of this report is to offer recommendations to address the expansion of invasive catfish populations and their impacts on living resources in the Chesapeake Bay. The report provides decision-makers an overview of the invasion and recommendations necessary to develop coordinated management strategies for the blue and flathead catfish invasion within the Chesapeake Bay watershed. Scope Although this report specifically applies to the waters and resources in the Chesapeake Bay watershed (Maryland, Virginia, Pennsylvania, District of Columbia, and Delaware), the Invasive Catfish Task Force (ICTF) recognizes that close coordination and cooperation is required with broader regional organizations such as the Atlantic States Marine Fisheries Commission, the Mid Atlantic Panel on Aquatic Invasive Species, Aquatic Nuisance Species 9

10 task Force and National Invasive Species Council. Invasive Catfish Task Force and Objectives The Invasive Catfish Task Force (ICTF) was established in 2012 by the Sustainable Fisheries Goal Implementation Team (Fisheries GIT) of the Chesapeake Bay Program and tasked with developing and recommending management options that could be applied Bay-wide to respond to the spread of invasive blue and flathead catfish populations in the Chesapeake Bay region. The ICTF is comprised of members from the fishery management jurisdictions of Maryland, Virginia, Pennsylvania, District of Columbia, Delaware, representatives from the Potomac River Fisheries Commission and National Oceanic and Atmospheric Administration (NOAA), academic experts from the Virginia Institute of Marine Science (VIMS), Virginia Commonwealth University (VCU), Smithsonian Environmental Research Center (SERC), and seafood marketing specialists from Maryland Department of Natural Resources and the Virginia Marine Products Board. The ICTF met several times in-person and via teleconference to compile and evaluate existing information on blue and flathead catfishes and to discuss potential management options. The ICTF also briefed the Fisheries GIT and stakeholders on draft recommendations during the preparation of this report. The ICTF developed recommendations to address the following four objectives: 1. Slow and reduce the spread of invasive catfishes into currently uninhabited waters; 2. Minimize the ecological impacts of invasive catfishes on native species; 3. Promote a large-scale fishery to significantly reduce abundance of invasive catfishes and provide economic benefits to the region; and 4. Increase outreach and education and broadcast the message that blue and flathead catfishes are not native to the Chesapeake Bay and negatively impact native ecosystems. Outreach is also needed to emphasize that public assistance is needed to 10

11 avoid additional unauthorized introductions within the Bay watershed. Overview of Invasive Catfishes (blue and flathead) in the Chesapeake Bay Introduction, Distribution, and Expansion Beginning in the 1960 s, blue catfish and flathead catfish were introduced to a small number of Virginia tributaries within the Chesapeake Bay region to create additional angling opportunities. Today, both species are now established in at least 10 major tributaries across Virginia, Maryland, and Pennsylvania. Initial stocking of blue batfish occurred in the 1970s and 1980s in the freshwater reaches of the Chesapeake Bay tributaries. Following introduction, the species rapidly expanded into tidal riverine habitats and are now commonly found in oligohaline and mesohaline waters of Chesapeake Bay tributaries, including all western shore rivers in Virginia as well as several Maryland and Eastern Shore tributaries. Flathead catfish were introduced to the James River, Virginia, between 1965 and 1970 and now occur in several Chesapeake Bay tributaries, including the James, York, Potomac, and Susquehanna rivers. Unlike blue catfish, flathead catfish are habitat specialists and generally prefer nontidal and tidal freshwater and oligohaline habitats. A geospatial model developed by VCU suggests that blue catfish distribution has the potential to nearly double from 136 watersheds (12-digit HUCs) to 242 watersheds in the Chesapeake basin (Figure 1). Flathead Catfish are also expanding their distribution in the region (Figure 2). 11

12 Figure 1. Current (solid polygons) and forecasted (cross-hatched polygons) distribution of blue catfish in Chesapeake Bay waters. Geospatial units are 12-digit watersheds (HUCs). Data are compiled from several sources, including VCU, VIMS, VDGIF, and MD DNR; data were current as of 1 April,

13 Figure 2. Current distribution of flathead catfish in Chesapeake Bay waters. Geospatial units are 12-digit watersheds (HUCs). Data are compiled from several sources, including VCU, VIMS, VDGIF, and MD DNR; data were current as of 1 April, Biological characteristics, such as tolerance for a wide range of environmental conditions, may further enhance the spatial expansion of newly established nonnative populations. For instance, blue catfish can tolerate salinities of 14 parts per thousand (ppt) or higher, which allows them to expand into estuarine reaches of tidal tributaries (Schloesser et al. 2011; Bringolf et al. 2005). The high salinity tolerance of these catfishes is not unique; channel catfish, another nonnative to Atlantic Slope rivers, also have a high salinity tolerance (Jenkins and Burkhead 1993). Unlike blue catfish and flathead catfish, this species has been established for over a century and is, therefore, unlikely to spread beyond its present range (Jenkins and Burkhead 1993). Range expansion of the blue catfish in Virginia tributaries has been previously 13

14 assisted by high river flows and episodic flooding (Edmonds 2003; Schloesser et al. 2011). Further range expansion of blue catfish may ensue when similar conditions co-occur (high abundance, high river flows). In Maryland, the unauthorized stocking or transportation of live fish by anglers appears to have aided the spread of blue catfish among tidal tributaries of the upper Bay. Similarly, redistribution of flathead catfish by anglers appears to play a major role in their dispersal in the Chesapeake Bay watershed. Flathead catfish are not as abundant as blue catfish (except in Pennsylvania where flathead catfish populations are a primary concern) and thus, populations may not yet exhibit dispersive movements in response to environmental cues. Ecological Impacts Flathead catfish and blue catfish are both considered invasive species, as recent studies have suggested environmental and economic harm to the Chesapeake Bay region as a result of these species introductions. The timing, sources, and possible implications of introduced blue catfish in Chesapeake Bay waters have been described recently by Schloesser et al. (2011). A similar synthesis concerning flathead catfish in this region is lacking. Blue and flathead catfishes share several biological characteristics that are believed to enhance the likelihood of their establishment in new environments. These include a diverse diet (including other fish), adult trophic status as apex predators, long life span, large body size, ability to tolerate a wide range of salinity, and parental care of young (Table 1; Morris and Whitfield 2009). These characteristics aid successful establishment of the non-native species and often lead to environmental harm to native species and their habitats. 14

15 Table 1. Common predictors of invasiveness for blue and flathead catfishes (adapted from Morris and Whitfield 2009). Propagule pressure refers to the density of individuals introduced, the number of introduction events, and the frequency of introductions. Invasive catfishes in Chesapeake Bay tributaries negatively interact with native fish and shellfish through predation and competition for habitat and resources. Ecological impacts from these interactions may include declines in native resident (Bonvechio et al. 2011) and anadromous (McAvoy et al. 2009) fishes. Blue catfish in these tributaries have a highly diverse diet and consume crustaceans, worms, bivalves (including native freshwater mussels), and fish, such as Atlantic Menhaden, American Shad, Blueback Herring, Bay Anchovy, and other blue catfish. The diet of flathead catfish tends to be dominated by smaller sized fish (>20 cm total length (TL) or >16.8 cm fork length (FL); Chandler 1998). Because both catfish species consume fish, and several fish species that use Chesapeake Bay tributaries are the subject of restoration or stock rebuilding efforts (e.g., Alosa spp.), blue and flathead catfishes have the potential to exert severe ecological harm to the region. Recent studies based on stable isotope analyses suggest that adult blue catfish and flathead catfish in these systems are novel apex predators that feed extensively on important fishery resources, including native resident and anadromous fishes (MacAvoy et al. 2009). Whereas preliminary studies have documented harm to native species, the full extent of 15

16 negative impacts from catfish invasions remains poorly understood. For example, coastal rivers within North Carolina and Georgia have associated flathead catfish piscivory with declines of some native fishes, including those of recreational importance (Pine et al. 2005; Bonvechio et al. 2011). Comparable studies for invasive catfishes in the Chesapeake Bay region are lacking though recent surveys suggest that invasive catfish predation on native species such as American shad, blueback herring, alewife, and blue crabs may be spatially confined. Piscivory by blue and flathead catfishes for instance is likely to vary seasonally and regionally, depending on habitat and prey availability. On finer spatial scales, we do not know how diets may be affected by depth; for example, catfish from shallow estuarine habitats may not exhibit the same pattern of piscivory as those from deeper estuarine areas. Furthermore, ecosystem-level effects of piscivory must take into account the size dependency of this feeding behavior. In blue catfish, piscivory is strongly size-dependent such that the frequency with which fish are observed in the diet increases with in larger fish sizes. Based on electrofishing surveys in the freshwater reaches of the James River in 2010, about 46% of the population of blue catfish was <31 cm fork length (FL), 47% was between 31 and 61 cm FL, and about 7% of the population exceeded 61 cm FL (n = 6,725 fish). In freshwater reaches of the Patuxent and Nanticoke rivers in , about 20% of the population sampled by low-frequency electrofishing was >30 cm total length (TL) and <1% exceeded 60 cm TL (n = 320 fish) (Hines et al., unpublished data). Nutrient enrichment has resulted in extremely high productivity in the freshwater tidal James and other bay tributaries, accommodating the presence of extremely high abundances of nonnative high trophic level predators including invasive catfish. Blue catfish are common bycatch in gillnet fisheries operating in Chesapeake Bay tidal tributaries. This may have economic consequences by reducing gear efficiency for target species. The amount and economic value of foregone harvest of the target species are currently unknown, but may be significant (Fabrizio et al. 2011). 16

17 Current Management Efforts Regulations and Policies In 2011, the Atlantic States Marine Fisheries Commission approved a resolution expressing concern about the impacts of blue and flathead catfish on Atlantic Coast migratory fish species. The resolution suggested that all practicable efforts should be made to reduce the population levels and ranges of non-native invasive species (ASMFC Fisheries Focus, 2011). Agreements between Chesapeake Bay jurisdictions and the Atlantic States Marine Fisheries Commission led to the development of various management options, the establishment of the ICTF, and the recommendation for this report. In January 2012, a policy statement ( 12_(with_signatures).pdf) signed by members of the Fisheries GIT Executive Committee concluded that blue and flathead catfishes are invasive and that the potential risk posed by blue and flathead catfishes on native species warrants action to examine potential measures to reduce densities and limit range expansion and to evaluate possible negative ecological impacts. While it is illegal in all jurisdictions to transport live blue and flathead catfish for the purpose of introduction into another body of water, a coordinated management strategy for blue and flathead catfish does not exist for Chesapeake Bay management jurisdictions. Maryland Department of Natural Resources, District of Columbia, and the Potomac River Fisheries Commission officials discourage release of angler-caught fish and are asking anglers to remove and kill any blue and flathead catfish that they catch, but the Virginia Department of Game & Inland Fisheries does not support a kill-on-capture policy. The Pennsylvania Fish and Boat Commission encourages anglers to kill all flathead catfish upon capture; however, this has never been implemented as a formal regulation. Current regulations for flathead catfish in Pennsylvania include a liberal creel limit of 50 fish per day with no minimum length or seasonal limitations. A draft management plan recommending measures to increase exploitation of flathead catfish within its non-native range is currently under review in 17

18 Pennsylvania. Commercial and Recreational Fisheries Catfishes in the Chesapeake Bay watershed have supported recreational and commercial fisheries for several decades. Commercial fisheries for catfish are typically low valued because of the price-per-pound has remained low, around $1/lb. Consequently, commercial extraction has been minimal (about 2 million pounds/year from tributaries of Chesapeake Bay in Virginia and Maryland). Both Maryland and Virginia are exploring the potential to develop new markets and hence increase commercial value of blue catfish. Important recreational fisheries have been developed, particularly in the upper James and Potomac rivers, where populations currently support lucrative trophy fisheries. According to the 2011 National Survey of Fishing, Hunting, and Wildlife-Associated Recreation, of the 27.1 million anglers who fished freshwater, other than the Great Lakes, 7 million were fishing for catfish and bullheads (U.S. Department of the Interior, U.S. Fish and Wildlife Service, and U.S. Department of Commerce 2011). The popularity of the catfish sport fishery stems from the ease with which these fish can be taken, the lack of economic barriers to participation in the fishery (i.e., fish can be accessed from shore, with minimal investment in gear), and the palatability of the flesh. These fisheries generate millions of dollars annually through angler expenditures and have been encouraged in recent years through state-wide competitions and tournaments. Maryland and Virginia recognize anglers through angler citation programs for trophy fish whereas the District of Columbia recognizes anglers that harvest blue catfish through a newly established records program. A primary reason for introduction of these species was to develop a recreational trophy fishery for blue catfish in Virginia. The current state record for blue catfish was set on June 18, 2011 at Buggs Island Lake with a fish weighing 143 pounds. The commercial fishery has a maximum size restriction of 32 inches in an attempt to minimize impacts on the trophy recreational fishery and to comply with the consumption advisory on this species (no consumption of blue catfish over 32 from the James River; 1 meal per month of blue catfish caught from other tributaries). 18

19 Research and Monitoring There are few monitoring programs focused only on invasive catfishes including fisheries programs at VIMS, VCU, VDGIF, SERC, District of Columbia Fisheries, University of Maryland, and MDDNR. These programs use a variety of gears to sample both the nontidal and tidal portions of the major coastal rivers. Other systems in Maryland such as the Rhode West Rivers have been sampled by SERC and University of Maryland, but these surveys have not yet encountered invasive catfishes. Where invasive catfishes have been detected, sampling can be used to infer changes in spatial distribution and relative abundance, diet composition, variations in age and growth rates, and concentrations of bioaccumulating contaminants (such as Polychlorinated biphenyls, Tributyltin, and Mercury (Hg)). A full summary of current research efforts and findings is provided in Appendix A of this report. Communication and Outreach Very little has been done to increase awareness among anglers or the general public with regard to invasive Blue and Flathead catfishes, the threat they pose to native species, or the No Transport regulations in effect. Maryland has partnered with the Chesapeake Bay Program to post signs at key public access sites to raise awareness. Information on websites across the jurisdictions is difficult to find and is not consistent, although Maryland, PRFC, and DC have taken action to improve messaging on invasive catfishes and communicate the no transport regulations. The issue of blue and flathead catfishes in the Chesapeake Bay and the draft recommendations in this report were presented to the Mid Atlantic Aquatic Invasive Species Panel and the Aquatic Nuisance Species Task Force. Further, the ICTF has communicated with catfish charter operators in Virginia on the invasion and associated impacts. The National Park Service and NOAA have offered to include information at their sites around the Bay but the details are still under negotiation. Recommendations It is important to note that although blue and flathead catfishes have been in the Chesapeake Bay for years, little has been done to manage these species. We are still working to 19

20 understand their biology and ecology and will need to test and evaluate the proposed management strategies for efficacy. The selection of appropriate management actions (e.g. prevention, eradication, control) in response to invasive fish species is often dependent on the life history characteristics of the species, size of infestation, and the ecology of the impacted community, (Kolar & Lodge 2001). Prevention is the most effective means to avert the risk of harmful introductions. Investment in prevention avoids many of the long-term economic, environmental, and social costs associated with invasive species. Once a species becomes established, control efforts require significant and sustained resources. Once a species has become widely dispersed in an open aquatic system like Chesapeake Bay eradication is rarely feasible or cost-effective (Sakai et al. 2001). The actions and recommendations outlined below focus on preventing additional spread of invasive catfish and the control of existing populations with emphasis on options to reduce impacts on vulnerable riverine and estuarine resources. Recommendations and the corresponding logic model (Appendix C) were developed within this context along with the anticipated long term effort that will be required to measurably change the current condition and realize the desired ecological outcomes. Each of the recommendations will require extensive discussion prior to implementation, broad cooperation among agencies, and a willingness to adapt strategies to new information as it becomes available (adaptive management). The following section includes ICTF context and findings used to formulate recommendations, the specific recommendations, and an analysis of the pros and cons of each recommendation. Recommendations are not listed in priority order. Recommendation 1: Removal from Priority Areas High abundance of invasive catfishes in the Chesapeake Bay region may be causing ecological harm by exerting predation pressure on native species such as blue crab, blueback herring, and Atlantic menhaden, and by competing with native predators. Invasive catfishes can also cause economic harm through interference with commercial fishing operations. Catfishes may be captured by commercial gear that targets economically-valuable species such as striped bass and may lead to a significant increase in the amount of time required to remove and handle 20

21 this unintended bycatch. We recommend that jurisdictions work together to design and implement targeted fisheryindependent removals of invasive catfish in places of significant ecological value (i.e. spawning and nursery habitat areas for anadromous species). Well-planned, intensive, and repeated removals of invasive catfishes may have the potential to reduce populations and lessen their impacts on important native species. We further recommend these removals be conducted as pilot projects or studies to develop, test, quantify, and evaluate removal methods for invasive catfishes. Existing GIS tools such as the Catfish Portal, Coastal GEMS, the Fish Passage Prioritization Tool and Maryland GreenPrint can be used by experts to identify prospective removal areas. A recent GIS-based analysis by VCU (Figure 3) identified 64 high-value Chesapeake Bay watersheds in Virginia and Maryland (i.e., below Conowingo Dam) that were at risk for establishment of blue catfish populations (n=9) or that already have established populations (n=55). These watersheds could be candidates for removals and increased preventative measures. Figure 3. Ecologically significant watersheds (red polygons) and streams (blue lines) in the Chesapeake Bay that occur within watersheds at high-risk by catfish invasions. Geospatial units are 12-digit watersheds (HUCs). Data were compiled by VCU from various sources. 21

22 In these high-risk areas, the goal is not to eradicate the invasive catfishes, but rather to limit their biomass and ecological impact. The use of electrofishing or piscicides as a control measure for invasive fishes may have the potential to reduce ecological impacts in some aquatic habitats, especially smaller systems with limited connectivity to source populations (Britton et al. 2010). For example, electrofishing removal (monthly for 33 months) reduced the abundance of invasive adult tilapia by 87% in an impoundment in northern Australia and resulted in a reduction in negative ecological impacts (Thuesen et al. 2011). Similarly, reduced abundance of an invasive mosquitofish population through removal efforts in a Spanish stream led to recovery of the two species with historical presence in the system (Ruiz-Navarro et al. 2013). Low-frequency electrofishing as a catfish removal method has the advantage of limited effects on non-ictalurids. Control projects of this type require a long-term commitment of resources to maintain low populations and monitor effectiveness of the program. Following removal operations, temporary deployment of constructed or non-physical barriers in smaller creeks may be beneficial to exclude adult invasive fish species (Noatch & Suski 2012). For example, excluding predatory invasive catfishes from tidal spawning habitats for native shad (Alosa spp.) during spring months may increase spawning success in those systems. Previously, VDGIF regional biologists used electrofishing in an attempt to eradicate invading blue catfish from the Piankatank River, Virginia. Although that effort failed, in part from limited departmental support, the upper Piankatank system (Dragon Run) may still be a candidate for a renewed removal pilot study in Virginia. Similarly the Patuxent River in Maryland and other Eastern Shore tributaries may serve as a test bed for removals and are currently under consideration Pro: Targeted removals may help mitigate impacts of invasive catfishes on native species in select tributaries. Con: Removals could be costly and may not significantly reduce numbers or ecological outcomes for native species. Disposal of removed fish may be problematic. One potential solution is to donate the fish to local food banks as this method has been used in other 22

23 nuisance or invasive species control programs (e.g., the Hunters for the Hungry, Target Hunger Now). Catfish removal programs may also spur conflicts with the recreational anglers. Recommendation 2: Develop Commercial Fisheries Debates concerning the appropriate management options for invasive species typically focus on documenting economic and ecological impacts and (if warranted) identifying feasible eradication or control measures (Sakai et al. 2001). In the case of introduced blue and flathead catfish in Chesapeake Bay, negative economic consequences may be mitigated at least in part by revenues generated from recreational and commercial fisheries for these species (Shogren & Tschirhart 2005). We recommended that efforts and incentives to develop a large-scale, commercial fishery be accelerated and coordinated across jurisdictions. Harvest incentives exploiting the growing populations of invasive catfishes have the potential to reduce populations while also providing economic benefit to the region. This will require more immediate and coordinated action across jurisdictions to identify markets, increase the value of the fishery, and remove factors (e.g. lack of processing facilities) that are currently limiting expansion of the existing small-scale fishery. A critical element of this recommendation is developing a fishery that is dedicated to reducing invasive catfish populations over the long term. We recommend a workshop be held with current and prospective fishers, fishery managers, and economists to identify the steps needed to expand the current fishery and make it economically feasible. To increase exploitation, the ICTF recommends developing a market for Chesapeake Bay blue catfish through marketing campaigns that promote the fishery as healthy and local. The Blue Ocean Institute has listed Blue Catfish from the Chesapeake Bay region as a seafood source ( Current data on mercury and methyl mercury concentrations in blue catfish indicate that these fish generally have levels below the EPA human health screening level, and current consumption advisories are no different than those applicable to striped bass. The ICTF recognizes that both Maryland and Virginia have efforts 23

24 underway to develop markets and suggests these efforts continue with coordination across jurisdictions. We note that Washington, D.C. restaurants have been successful in promoting blue and flathead catfishes as local, fresh catfish on their menus and suggest implementing similar measures throughout the Bay watershed. Pro: Developing a commercial market may help raise the value of catfish and encourage additional fisheries to targeting invasive catfishes through the Bay. In turn, this harvest may reduce catfish abundance and decrease bycatch interference in other commercial fisheries. Such actions that rebuild and sustain native species (and associated fisheries) provide longterm economic gain. Con: Developing a commercial market to raise the value of an invasive species may lead to pressure to manage the fishery for sustainable harvests, contradicting the initial objective of population reduction. Further, successful efforts to increase demand and market value may increase the threat of unauthorized introductions into new waters to create fisheries. Recommendation 3: Evaluate Removal Methods We recommend jurisdictions consider options to incentivize increased harvest operations for invasive catfishes by small boat operations and electrofishing. These options could be further discussed as a part of the workshop suggested in Recommendation 2. As recommended by the ICTF, If may be ideal for commercial industries to begin with offering incentives to small-boat operations (2-3 people), for example free licenses for the capture and sale of invasive catfish may be provided. This may increase harvest and promote profitable small-scale operations. Electrofishing as a commercial fishing technique has been around for many years (Fitz 1970), but for many reasons, including cost, safety, and effects on non-target species, it is not widely applied. However, in nontidal, tidal freshwater, and oligohaline reaches of larger Chesapeake Bay tributaries, the use of low-frequency ( 15 pps), pulsed direct current (PDC) electrofishing 24

25 by commercial catfishers could lead to the harvest of large numbers of blue catfish. Whether or not commercial LFEF electrofishing could be an effective (i.e., ecologically relevant) control measure for blue or flathead catfish is currently unknown, but electrofishing has the advantage of limited by-catch (cp. gillnets) and low habitat impacts (cp. bottom trawls). Electrofishing is restricted to specific seasons (water temperatures between 18 and 25 C) and locations ( 2 ppt salinity) and may be subjected to variable market demand and contaminant issues similar to other fisheries. Experimental electrofishing for commercial applications would require a significant financial investment ($20K per vessel) and strict oversight by agencies, this investment may be fundable through fishery resource grants or similar programs. North Carolina currently allows recreational (but not commercial) catfish harvest by electrofishing, with specific restrictions (T. Kwak, NCSU, pers. comm.). We note that at least one proposal has been submitted to the Fishery Resource Grant Program of Virginia Sea Grant to explore the feasibility of using electrofishing gear for harvest of blue catfish. Similar evaluations of gear efficiency may promoted within other organizations. Pro: Incentives and gear allowances may promote a fishery and help increase landings of blue catfish, reduce biomass, and reduce impacts on native species. The fishery may also provide economic opportunities. Con: Developing a market and raising the value of an invasive species may pressure agencies to manage the fishery for sustainable harvests, contrary to the initial objective. Competing objectives could also arise between small-scale operations and recreational fishing, however, if only smaller fish are targeted by electrofishing then these conflicts should be minimal. There is also the possibility that native white catfish could be accidently removed if species identification is not emphasized. There are regulatory and legislative barriers to allowing catch of recreational fish to be sold in addition to possible safety concerns and fishery enforcement challenges, which may create challenges to implementation. Recommendation 4: Develop Monitoring and Response Plans 25

26 Invasive catfish populations are rapidly expanding across tidal and nontidal reaches of the Chesapeake Bay watershed. As previously shown in Figure 1 and 2 blue catfish distribution and flathead catfish are expanding across the region. We recommend jurisdictions establish monitoring programs dedicated to identifying and tracking invasive catfish distributions and population status. There are currently few dedicated monitoring and survey efforts for invasive catfishes; accordingly, we also recommend developing early detection and response programs to monitor ecologically significant areas. Research efforts in regards to the catfish invasion in the Chesapeake Bay should be synthesized and used to improve effective implementation and refinement of the management options outlined in this report. Effective surveillance programs are essential for the management and potential control of invasive species but such programs are very expensive to maintain, especially across large areas. Opportunities to leverage existing resources (e.g. acoustic telemetry arrays) or new technologies (e.g. molecular genetics (edna), online data portals) should be identified and pursued as part of an overall strategy for monitoring the distribution and spread of blue catfish and flathead catfish in the region. For example, the recent development of environmental DNA (edna) analyses as a relatively inexpensive and accurate way to detect Asian carp and other biological invaders (Darling and Mahon 2011) in aquatic habitats could be applied to Chesapeake Bay surveillance programs for catfish and other aquatic invasive species. Another example of surveillance is the use of smartphone apps that allows recreational and commercial fishers to upload photos and locations of captured blue catfish. SERC is using the citizen science smartphone app, called Project Noah, as one tool to study the spread of blue catfish throughout upper Chesapeake Bay. Backed by National Geographic, this app is used to collect catfish distribution information from commercial and recreational fishermen. The app is free to download and can be viewed at 26

27 The concept of using recreational and commercial users to help identify and document invasive catfish distributions using mobile devices could be applied more broadly in the Bay. Therefore, we also encourage continued support to improve understanding of invasive catfish biology, their ecological impacts, and potential control mechanisms. There is still much to be known about the role of invasive catfishes as predators in the Chesapeake Bay region in spite of recently-completed and ongoing studies supported by NCBO, ASMFC, VDGIF, and others. Basic biological information about these species remains largely unknown including reproductive potential, salinity tolerance, and bio-energetic demands. Efforts should continue to improve our understanding of the mechanisms that contribute to the spread and success of invasive catfishes in the Bay region. The ecosystem is not static and there may be changes we cannot anticipate that will enhance the ability of catfish to invade other areas. Applied research efforts will also assist in the development of new tools and more effective management approaches. Pro: Improved monitoring would provide better distribution and population status of invasive catfish species. Continued research and synthesis will allow for new tools and adaptive management strategies. Con: Effective monitoring requires long-term commitment of resources, interagency coordination, technology development and public participation. Recommendation 5: Evaluate Habitat Connectivity Over 3,800 constructed impediments to fish migration (mostly low head dams) are documented on Chesapeake Bay tributaries (E. Martin, TNC, unpubl. data). Many have been prioritized by wildlife resource agencies for removal or for other construction activities by fish passage facilities to support regional diadromous fish restoration goals. Approximately 10 percent of these structures are identified as high priority (Tier 1 & 2) for removal in the near future. In most circumstances, removal of a dam will significantly increase the ecological health of a river by restoring its hydrologic connectivity to the watershed (Holmquist et al. 1998). 27

28 However, some have argued that the benefits gained from successful fish passage projects may be offset by opening corridors to invasive species that had previously been blocked from upstream reaches (Freeman 2002). For example, the Bosher s Dam fishway on the James River allowed passage of at least 8,000 blue catfish between 2002 and 2005 (Fisher 2007) and the species is now well-established upstream as far as Columbia, Virginia. Similar information may be available for flathead catfish on the Susquehanna River at the Conowingo Dam in Maryland. We recommend an evaluation of the effectiveness of existing barriers to invasive catfish spread (i.e. dams) and suggest that the benefits of barrier removal be weighed against the risk of damage to areas of significant ecological value by invasive catfish range expansion. We suggest formal coordination between invasive catfish experts and the Fish Passage Workgroup of the Chesapeake Bay Program Habitat Goal Implementation Team to identify barriers and develop ecosystem-based recommendations that address the risk of additional invasions following dam or other barrier removal efforts. This may include requiring an assessment of the unintended consequences as part of the fish passage prioritization process, including creation of expansion corridors for invasive species, before removing or modifying Tier 1 & 2 dams. This requirement may be especially needed for Tier 1 or 2 dams within high-risk catfish watersheds, as identified by VCU s spatial model (Figure 4). 28

29 current as of 1 April, Figure 4. Tier 1 (red) and tier 2 (yellow) dams prioritized for fish passage in watersheds that currently support blue catfish (solid polygons) or at risk to support blue catfish (crosshatched polygons). This analysis is limited to Chesapeake Bay waters below Conowingo Dam. Geospatial units are 12-digit watersheds (HUCs). Data are compiled from several sources, including VCU, TNC, VIMS, VDGIF, and MDDNR; data and Pro: Formal consultation in regards to the risks of invasive catfish expansion as a result of dam removal could help limit the spread of invasive catfish and foster collaboration between fishery managers and habitat restoration specialists. Con: The benefits of providing access to habitat for species like American shad, river herring, and American eel may outweigh costs of invasive catfish range expansion. Studying invasive catfish expansion risk could increase cost, extend timelines, and potentially prevent some dam removals. Dams that are left in place to prevent upstream expansion by invasive species are still subject to the possibility of illegal transport upstream by anglers. 29